Among refrigerant compressors, what is called an open-type refrigerant compressor has a housing in which a compression mechanism is accommodated and a rotating shaft one end of which protrudes from the housing toward the outside so that it is driven by an external drive source. In such an open-type refrigerant compressor, the portion of the housing through which the rotating shaft penetrates needs to be sealed so that the interior of the housing is hermetically sealed from the atmosphere. A mechanical seal has come to be used for the sealing, as high pressure refrigerants such as R410A and CO2 have come to be used recently. The mechanical seal commonly has a stationary ring securely fastened to the housing and a rotary ring securely fastened to the rotating shaft. The mechanical seal is configured so that the rotary ring and the stationary ring are spring pressured into sliding contact with each other over a relatively small area, which achieves the shaft sealing function.
The high pressure refrigerant R410A has operating pressure about 1.5 times to 4 times higher than, for example, R407c and R134a, so it tends to result in a greater amount of heat generated at the contact sliding parts of the mechanical seal. On the other hand, even the mechanical seal is not free from leakage of lubricating oil from the contact sliding parts, and there are cases in which a very small amount of lubricating oil leaks out. When the lubricating oil that leaks from the contact sliding parts stays around the stationary ring, the lubricating oil degrades because it is exposed to the high temperature generated at the contact sliding parts, turning into sludge, which is deposited around the stationary ring. The sludge deposited in this way may be caught in the contact sliding gap. This may damage the contact sliding parts and can bring about problems such as degradation of the shaft seal and increase of lubricating oil leakage.
In view of this, in order to prevent the lubricating oil leaking from the sliding surfaces from staying around the sliding surfaces and turning into sludge, Patent Reference 1 discloses a refrigerant compressor having the configuration as follows. An oil accommodating space is formed further inward than the contact sliding parts by a rotary ring, a stationary ring, and the outer circumferential surface of a rotating shaft. An oil supply passage provided in the rotating shaft is provided with an opening into this space, so as to form a path through which oil is circulated at all times. This circulation of the oil is intended to prevent drying out of the oil and generation of blisters at the contact sliding parts, and generation of sludge around the contact sliding parts. Moreover, it is intended to move the oil leaking from the contact sliding parts in a direction away from the vicinity of the contact sliding parts by a centrifugal force so as to prevent building up of sludge resulting from the oil staying around the contact sliding parts.
Patent Reference 1: Japanese Unexamined Patent Application, Publication No. 2006-242061